Sorry, you can tell when I'm typing on my phone because my answers don't ramble on like usual. :)
Your description seems more like an Intrimik or Holtest gauge rather than a dial bore gauge. The primary differences being that the former typically has 3 points of contact in the bore and a rotating thimble to bring them into contact and obtain a direct measurement. The latter is zeroed to the desired measurement using a standard (setting stand with gauge blocks, micrometer, or similar) and has only 2 points of contact. The latter is rocked around until the largest measurement is found. Spring pressure keeps the points in contact with the bore. The dial shows the difference between the set value and the measured diameter.
I'm thinking that the Dial Bore Gauge operates similarly but that's only me looking at the outside and making an educated guess. I was looking for confirmation of the more concrete type.
These videos are ONLY for illustrative purposes. I haven't watched them entirely or validated the content.
Dial Bore Gauge:Holtest: